Sulphide odours are tainted aromas in drinks fermented with yeast especially wines which, depending upon their stage of development, remind one of putrid eggs, burnt rubber, burnt onions, sweat or the like.
The reason for the occurrence of these sulphide odours is that thiols are formed by the yeast in the course of the fermentation process. The initially formed thiols react with other constituents of the drinks to produce ever more complex sulphurous compounds which are all particularly strong smelling. It is self-evident that such foul smells are off-putting especially in wines.
A whole series of measures have been developed for eliminating sulphide odours in wines. One widely used method involves the addition of food-compatible cuprous salts such as copper sulphate for example because the copper ions are able to bind the sulphur compounds. However, such measures can only be carried out before filling the bottles.
Not infrequently however, the sulphide odours recur even after a successful treatment or they develop for the first time after the bottles have been filled. Responsible for the occurrence of the odours in these late stages are thioacetic acid esters which themselves are odorously inactive. During storage, other substances which exhibit increasingly higher odorous intensities are formed from the thioacetic acid esters in a chain reaction.
The thioacetic acid esters giving rise to the late sulphide odours do not react with copper ions. They represent an initially masked precursor stage which cannot be preventively removed by treatment with cuprous salts. Consequently, even wines which have once already been treated with cuprous salts are not protected from a fresh occurrence of such sulphide odours. The economic damage which occurs due to sulphide odours developing in the bottle, in premium wines to some extent, is substantial.
There was therefore a need for a measure with which sulphide odours could be eliminated even in wines that have already been filled into bottles.
It is self-evident that a measure of this type is not limited to wines but is equally suitable for other drinks in which there is a tendency for sulphide odours to form such as fruit wines, distillates etc. for example.